Devices for utilizing wind energy to generate power tend to be of either of two types. The first of these is the usual wind mill configuration, which may be referred to with somewhat greater dignity as a wind-turbine. These devices must necessarily have an axis of rotation in fairly close alignment with the wind direction in order to produce power. The other type of device utilizes a rotor mounted for rotation on an axis transverse to the wind direction, and which may be either horizontal or vertical. The vertical type has the great advantage of responding to wind from any direction without requiring a shifting of its mounting. The present invention is associated with a form of this type of device in which the wind impinges on the surfaces of articulating airfoils that change position in cycles as the rotor assembly revolves. Machines operating on these principles have been known for many years, and typical examples have been noted in the following U.S. patents:
______________________________________ PATENT NUMBER: INVENTOR: DATE OF ISSUE: ______________________________________ 598,479 Hoover 1898 3,604,942 Nelson 1971 3,743,848 Strickland 1973 ______________________________________
The use of triangular sail-type panels as articulating airfoils is disclosed in the Monney U.S. Pat. No. 2,633,921, which provides for a pivotal relationship between the sail panels at an apex of the triangular configuration, and also at the side opposite from the apex by providing what amounts to a pivotal connection of a boom to a supporting structure. The Monney patent, however, is associated with a horizontal-axis rotor functioning in the manner of a wind mill, with the sail articulation being used solely to control the angle of attack of the sails with respect to a constant wind direction. A biasing effect is also shown in this patent, which is also limited to the decrease of the angle of attack in response to wind pressure.
The primary design criteria of the present invention is the improvement of the power-cost ratio through the use of maximum simplicity and readily-available inexpensive materials. To eliminate the need for incorporating governing devices, it is very desirable that a rotor assembly should have inherent speed-limiting characteristics to eliminate possible damage to the rotor and to the associated power-generating equipment during periods of excessive wind velocity.